Cross-linked Polyamides Prepared through Direct Bulk Michael Addition and Polycondensation from 1,6-Hexanediamine and Methyl Acrylate

Cross-linked polyamides (cPAs) were prepared through direct bulk Michael addition and subsequent polycondensation. Several mixed hexanediamine multi-esters (HDAMEs) were generated through the Michael addition of 1,6-hexanediamine (HDA) and methyl acrylate (MA) at 50 °C with different HDA/MA molar ratios. Melt polycondensation of HDAMEs then proceeded at 150 or 170 °C in flasks to obtain viscous fluids, and curing was continued in tetrafluoroethylene molds to obtain cPA films. The Michael addition was monitored on the basis of FTIR and ESI-MS spectra. The cPA films were characterized by DSC, TGA, dynamic mechanical analysis, and tensile test. These directly prepared cPAs exhibited T g of 1–39 °C, tensile strength of up to 45 MPa, and strain at break from 18% to 40%. The cPAs with high tensile strength and good toughness were successfully synthesized through the direct bulk Michael addition from HDA and MA followed with polycondensation.